NordicCNC's build log

[JAZZCNC]

I don't use F360 but would imagine it works just like Solid works where it will allow you to import Step or Stl models which if Hi-win don't supply a direct F360 format like they do for SW you could use. DXF is mostly a 2D format and you want a 3D model.

Also for Component models I use Traceparts
https://www.traceparts.com/en

[joe.ninety]

Also for Component models I use Traceparts
https://www.traceparts.com/en

Thanks for that tip. Looks like an interesting site.

Cheers

[NordicCnc]

@NordicCnc

Can I ask you a couple of questions regarding your CAD drawings that you're posting here...

1. Were they done using Fusion360?

2. Have you modeled all the elements yourself, like the carriages and rails etc, or have you just found existing DXF files and imported them?

3. If imports then could you share the source?

I'm asking because I'm using F360 and am having real problems with the dimensions of my imported DXFs. I've been using DXFs from the HiWin website, but whenever I import them into a design the dimensions are all out. The imported DXF are never the same dimensions as they are on the 2D drawings, so aren't really useful.

All I'm doing at the present is just using solid shapes to represent the items I want. So a HGH20CA carriage for example is a block 77.5 x 44 x 25.4 with a channel running through it to represent where the rail goes.

Looking at your design drawings, you seem to have everything fine?

Cheers

I use Siemens NX which I am lucky enough to have a work related license for. If I wouldn't have that I would probably be using Fusion 360.

The linear rails and blocks are downloaded as STEP files from the hiwin configurator: https://motioncontrolsystems.hiwin.c...near-guideways

The ballscrews I have modeled myself without any threads. This is because I want to model the ballscrew F-lengths myself, and I have no need for the thread visualization anyway

I also use traceparts and grabcad for other models like servo motors. I like the STEP format best, no issues so far!

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[joe.ninety]

@NordicCnc

Thanks for that tip re the Step files. I went back in and re-downloaded all the files as 'Step' and my problems went away.

The only problem with the rails is that you need to specify a length before the website will create the 3D file for you. Think I'll knock up my own version and just keep that as a 2D drawing that can be extruded to the length required. Although it will obviously lack the actual positioning of the mounting holes.

Cheers

[JAZZCNC]

@NordicCnc

Thanks for that tip re the Step files. I went back in and re-downloaded all the files as 'Step' and my problems went away.

The only problem with the rails is that you need to specify a length before the website will create the 3D file for you.

Just get a few different lengths and lay them on top of each other, aligning with each bolt hole to keep the spacing. It's always better to work accurately and mate the bearings to the surfaces of the actualy rail they would run on, this way you don't get accumulative errors building up as the model grows.

[NordicCnc]

Short update:

No progress for the last 2 weeks on the router design. I have been really busy with other projects and commitments. I had already bough 180W servos but those I already returned for some 400W servos with integrated drives. Those servos are now fitted on a Hitachi Seiki lathe (huge lathe with 400mm 4-jaw chuck) with a 1:1 ratio on the X-axis and a 2:1 ratio on the Z-axis. Ballscrews are 2005. WOW, I can now run the lathe at 10m/min without any problems. Ballscrew whip is no problem. I am very happy with that upgrade.

Anyway back to the router. Since I will be using servo motors with a 3000rpm rated speed, I thought I could take full advantage of that. I plan to do the following:

• Swap the 2010 ballscrews to 2020 on the Y-axis and X-axis.
• Swap the 1605 ballsrew to 1610 on the Z-axis
• Change gearing ratio from 2:1 to 3:1 on all axis. This will give me more torque, with lower ballsrew rpm while increasing the ballscrew pitch.
• Add belt tensioners to get more teeth engaged because of the 3:1 gearing.

This will limit the ballscrew speed to 1000rpm, and increase the Y- and X-axis maximum feed rate to 20m/min. Z-axis feed rate will stay at 10m/min. I feel like this is a better idea than trying to spin the ballscrews at 1500rpm with the 2:1 ratio. I want to take full advantage of the servo motors RPM.

On another note I was planning to use 400W (maybe even 750W) Delta servo motors, with dual motors on the Y-axis. I need to do some calculations if it would be a good idea to go for 750W. Anyway I saw on YouTube that there is a auto tuning function available in the software but I am not sure how to tune the dual motors on the Y-axis.

1. What do you guys think about the increased ballscrew pitch, 3:1 gearing and belt tensioners?
2. Is it possible to auto tune 2 motors at the same time?
3. Perhaps I could change the design and use only 1 servo motor on the Y-axis with belt drive connected to both sides. This in turn will not allow for squaring the gantry with motion controller but I think i can get it square any way.
4. How wide can the gantry be without having to use dual slaved Y-axis motors?

[Gustave]

Hi,

from #111 "Perhaps I could change the design and use only 1 servo motor on the Y-axis with belt drive connected to both sides. This in turn will not allow for squaring the gantry with motion controller but I think i can get it square any way."

I am face to the same question and first thought is doubling motor + driver + home switch is a costly option compare to 1 motor + belt drive... Have you develop the track of 1 motor for the both Y with belt drive ? Could you advice buildLog of thread that discuss this point ?
Regards

[NordicCnc]

Hi,

from #111 "Perhaps I could change the design and use only 1 servo motor on the Y-axis with belt drive connected to both sides. This in turn will not allow for squaring the gantry with motion controller but I think i can get it square any way."

I am face to the same question and first thought is doubling motor + driver + home switch is a costly option compare to 1 motor + belt drive... Have you develop the track of 1 motor for the both Y with belt drive ? Could you advice buildLog of thread that discuss this point ?
Regards

No I didn't go for that. I did alrady buy the components fpr dual drive Y-axis and they are being shipped currently. I never looked into the design either. I bet it could work, but perhaps it is not ideal in my case for a 1200mm gantry!

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[NordicCnc]

So machine design is now what I consider 99% completed so that I can start ordering parts. Since none replied on the ballscrew change I've decided to do the following:

- Keep the 2:1 ratio
- Change Y- and X-axis ballscrews to 2020
- Keep the Z-axis ballscrews as 1605
- No belt tensioners
- Double Y-axis motors will be used


I will put together a shopping list for all components so that I can get as much as possible in one order without missing anything. The final piece of design was to find a good location for the Y-axis home/limit switch. Cable chains I will fit later and wont add those to the 3D at all. Please ignore that the screw is not in the center of the limit switch. I will lathe and mill some custom screws but I could not care to design those yet.



Final assembly!



Some things still bugging me is the 120x80 for the gantry. I hope that those will not be too weak for machining aluminium with the ATC spindle. I am still consider changing to 160x80. JAZZ, if you read this, I remember that you wrote somewhere that for larger machines you use the 160x80 for the L-shape gantry. Since my gantry is 1200mm wide and I am using an ATC spindle, would it be wise to go for 160x80 anyway?

[joe.ninety]

Can I just ask what the benefit is of using blocks of profile to sit the gantry profile on, as indicated in the picture?



It seems because of this you were forced to place the bottom linear rail on the front, thereby pushing the spindle further away from the gantry. I'd always though that the idea is to try and keep the centre of gravity of the spindle as close as possible to the bearing blocks the gantry rides on.

This is not in anyway meant to be a criticism, but just me trying to understand if this design means there are benefits to it that outweigh the spindle being pushed further outward.

Cheers